Right now, wastewater treatment accounts for roughly three percent of the electricity consumed in the U.S.—but not for long.
Scientists have known for a while that microbes produce electricity, but no one has managed to get them to produce enough of it to matter. That just changed. Researchers at the Oregon State University have developed a new kind of microbial fuel cell that produces electricity as it cleans water. The OSU breakthrough tops previous attempts by generating 10-to-50 times more zap than current models (and 100 percent more than low producing variations).
To pull this off they took advantage of a number of recent engineering advances—reduced anode-cathode spacing, evolved microbes and novel separator materials—though the fundamental process is pretty straight-forward: special bacteria (those evolved microbes) are introduced to organic waste material. As the waste begins to oxidize (thanks to the bacteria), electrons are produced. These run from anode to cathode and thus create an electric current.
How much current? Current designs can produce two kilowatts per cubic meter of liquid reactor volume and without any drawbacks (some models produce methane as a by-product, this tech does not).
So how much electricity could this produce nationwide? Well, we generate about 8 million tons of sludge annually (this accounts for 30-80 % total electricity in wastewater treatment). On top of that, we also treat about one billion gallons of non-potable wastewater a day. Theoretically, there’s energy available from both sources—meaning the upside could be big.
The best news is that unlike many disruptive technologies this one does not have any ridiculous barriers to entry. The OSU team built a substantial lab model and see a clear path to scale. Once early costs drop, the researchers believe this version could undercut current wastewater treatment plants.
The impact of this tech domestically is substantial, but the real excitement is in the developing world, where wastewater treatment plants tend to be far and few between and electricity is seriously in need.
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